Synthesis of large-size β–Si₃N₄ crystals

Large-sized β–Si₃N₄ crystals up to 10 mm in length and 0.3 mm in diameter with low impurity concentration are successfully grown from silicon melt in a nitrogen atmosphere. By controlling the concentration of impurities in the silicon melt, a new kind of β–Si₃N₄ crystal, that is, a transparent coloring one with an absorption edge around a wavelength of 520 nm, is obtained.